My fan won't run except on low. There is no option to change the fan speed. The fan control only allows you to set the time you want it to run. I had a Honey... thermostat with the exact same wires in the same letter codes. Wires Y1, Y2, G, OB, Rc, W2 aux, C. Nest Model A0013., With the outside temp about 85" the temp inside would not go down to 76" which I had the Nest set to, in fact it ran all day and lost ground (got warmer in the house). I even removed the filters to allow more air in. About 8" from the vent you could not feel the blowing at the vents. I think it was blowing at low speed. My fan motor in the blower unit only has wiring to the C (Full speed) terminal on the fan (B,C have no wires). Reconnect my old Honey... thermostat at 1:00 A.M. Same exact wiring code letters, put the filters back in place. About 20 minutes I went down to see if it had made a dent to get down from the 78' it was inside to the setting of 74". It was already down to 74" and the heat pump cycled off. The Nest ran all day and the temp inside actually went up! Heat pump w/ aux heat, electric powered, no other fuels. The Nest test confirmed all 7 wires were connected, fan test was good.
